The Application Of Poly (3,4-ethylenedioxy Thiophene) In The Neural Interface

Neural engineering is a discipline within biomedical engineering that uses engineering techniques to understand,repair,replace,enhance,or otherwise exploit the properties of neural systems.As a kind of device,implantable electrodes are widely used in the areas of neural engineering,such as the treatment of epilepsy by deep brain stimulation with implantable microelectrodes.Especially in the neural interface,implantable electrode is an important component,its performance directly related to the collection and analysis of the data,which has a significant influence on the results of the study.In recent years,the study of implantable electrode is mainly concentrated in two aspects: one is to design a new structure of the microelectrode,satisfy the requirements of the experiments.On the other hand is the using of new materials and modifying the electrodes,so as to chronically and stably record or stimulate the neuron activity.Conducting polymer is widely used as materials for modify the microelectrode due to its excellent electrical properties and biological compatibility.Especially polymer poly(3,4-ethylenedioxy-thiophene)(PEDO T)which with good stability,conductivity and biological compatibility,is one of the most common materials used for modify microelectrode.This work is using conductive polymer poly(3,4-ethylenedioxy-thiophene)(PEDOT)to modify implantable electrodes by the way of electrical deposition.We use a small molecule surfactant(Sodium Dodecyl Sulfate,SDS)instead of polymer(Sodium Polystyrene Sulfonate,PSS)as doping agent.We compare the difference between the materials on the morphology,roughness,adhesion,and the electronic properties,etc.The results indicate that the morphology of PEDO T changed granular into porous-like using small molecule surfactant instead of polymer as dopant.The surface roughness is from 17 nm to 140 nm.The adhesion between PEDOT and the microelectrode surface will be improved,too.Ultrasound 20 minutes,the impedance of PEDOT doped with SDS increased 3.2 times on average,compared to the impedance of PEDOT doped with PSS increased 12.3 times.It indicates that the adhesion force between PEDOT doped with SDS and the microelectrode surface is stronger,can resist the destruction of the mechanical force and maintaining the impedance.Through the analysis of impedance spectroscopy and cyclic voltammetry,assess the ability of recording neurons signal and the stability of electrical properties.The impedance reduces about 50% and the stability increases by 3.5times.Compared the difference of neural microelectrode modified with different materials in the detection of dopamine,finding that PEDOT doped with small molecule is more suitable for detection of concentration vary in a wide range.Experiments show that PEDO T doped with small molecular surfactants has higher surface area,better adhesion and more stable electrical performance,which is more suitable as a material to modify neural microelectrodes.